Device for producing colored pictures



Nov. 14, 1933. R. RUDENBERG 1,934,821

DEVICE FOR PRODUCING COLORED PICTURES Filed May 28, 1952 51mm MM MM,

Patented Nov. 14, 1933 UNITED STATES PATENT OFFICE Reinhold Riidenberg, Berlin-Grunewald, Gerassignor to Siemens- Schuckertwerke Aktiengesellschaft, Berlin-Siemensstadt, Germany, a corporation of Germany Application May 28, 1932, Serial No. 614,279, and in Germany May 30, 1931 4 Claims.

My invention relates to electron oscillographs of the type in which the image forms a surface.

By means of moved electron rays,the intensity of which is periodically varied, it is possible to produce a moving image on a luminous or fluorescent screen by causing the rays to sweep or scan over the screen in regular lines.

According to my invention, the luminous screen and the variation in the intensity and the motion of the electron ray are so arranged that the moving image appears in natural colors.

My invention is illustrated in the accompanying drawing, in which Fig. 1 represents a longitudinal section through a cathode ray tube provided with means for directing the rays to perform the scanning motion;

Fig. 2 represents a luminous color screen partly ruled for diiferent colors;

Fig. 3 shows diagrammatically scanning of the screen in the direction of the color ruling, and

Fig. 4 shows diagrammatically scanning of the screen at right angles to the color ruling.

In Fig. 1 of the attached drawing the diagram of the electron tube is shown, in which an electron beam propelled from a cathode k and passing through an arrangement of diaphragms b and an arrangement of deflecting plates a falls on the luminous screen s and travels over same in regular periods.

The luminous screen in this case is not provided with a uniform coating but has variously colored luminous places distributed similarly to the manner employed on screens for three-color photography. For this purpose the screen may, for example be coated with three different kinds of salts which become luminous under the action of the cathode rays impinging upon them.

It is for many purposes sufficient to employ a line or ruled screen as shown in Fig. 2 in which each of the three prime colors is spread out along a whole line and the different lines with the three prime colors side by side recur in cyclic succession. A screen of that kind is relatively easier to make than a spotted screen with a regular distribution of spots in the individual colors. It is advantageous not to fix this screen against the wall of the vacuum tube itself, but to make the luminous screen separately and mount it in the vacuum tube as shown in Fig. 1 at s.

If the spot of light produced by the cathode ray is by means of a suitable control of the changes on the two pairs of deflecting plates a in Fig. 1 now caused to travel line for line over the screen in the manner coarsely shown by Fig.

3 and to move substantially along the lines of the screen, the various lines will gleam in accordance with the occurring variations in intensity of the cathode rays. The variation in intensity can, for example, be eiiected by the diaphragms 1), whose static charges are assumed to vary with the required intensity of the rays. If the variation is controlled from a transmittr through means suitable for that purpose in the manner corresponding to the distribution of the colors of any natural picture or object, an image of the living object or moving picture will be produced in natural colors on the screen s.

In order to obtain the same number of spots or points of the whole image as with a black and white image, it would with three-color luminous screens be necessary to employ three times as many lines to be scanned. As, however, the individual impressions of the various color eflects overlap in respect to space and time, such a large number of lines are not necessary. The number of spots or lines required is but little larger than for black and white images. Contrary to Figs. 2 and 3, the electron beam may also be caused to scan the screen at right angles to the color ruling of the screen, as indicated in Fig. 4.

While in that case the scanning need not be as close as in the modification Fig. 3, the variations in intensity of the rays on the other hand must take place in one-third of the time, since three color impressions must always be transmitted successively for each analyzed picture unit, and the variation in intensity must reproduce these diflerent color impressions correctly with respect to time.

While with the monochromatic image its size on the screen, which depends upon the speed and the control with respect to time of the cathode ray, may be chosen at will, this is with the described colored images under certain conditions no more permissible. In order to make the fluctuations in intensity impressed upon the electron ray coincident with the correct color line of the screen, the size of the image must be correctly set, so that the spot of light is always at the right time on the line of the screen for the desired color. When the ray scans the color screen according to Fig. 3 the setting of the size is more easily efiected than when the ray scans the screen across the color ruling as shown in Fig. 4.

The transmitter corresponding to theabove described receiving arrangement must of course be so made that, whilst a colored line of the screen is being crossed by the electron beam of the receiver, a change in the intensity of the electron ray is produced by the transmitter corresponding to the change in intensity of the component of the same color of the light sent out from the same position of the screen of the picture to be transmitted.

In such a transmission the ray of light, leaving the object of which the image is to be produced, or, for example the light falling through the colored film to be transmitted, is directed upon the color filter of a photoelectric cell. When at the transmitter the first line of the screen is crossed by the ray of light, the ray enters a .filter which only allows a certain color to pass corresponding to the color of the first line of the screen at the receiver. When the second line of the screen at the transmitter is crossed, a filter for another color, corresponding to the color at the second line of the screen at the receiver, becomes effective. At the third line of the screen, the third color filter becomes eflective. While thus the various lines of the screen are crossed, the electric cell is illuminated with a changing intensity which corresponds to the changing intensity of the color component allowed to pass at the time and which produces at the receiver a corresponding intensity of the same color component. Instead of operating with filters, the picture to be transmitted, for example a colored picture, may under certain conditions be illuminated in definite succession with lights of difierent color. This can be done, for example, by providing for the switching in or the becoming effective, in a certain alternation of colored lights produced in' discharge tubes.

I claim as my invention:

1. In a receiver for television or the like, a cathode ray oscillograph tube having a luminous picture-reproducing screen, and means for varying the ray intensities in accordance with the intensities of the transmitted picture points, and means for causing the ray to scan over said screen in a given direction, said screen having a parallel ruling of recurrent, similar groups of at least three lines each, each line of a group having a color different from the colors of the other lines of its group, said differently colored lines being formed by coatings of different salts, ditferently luminous under the influence of a cathode ray, whereby the transmitted picture is reproduced by the cathode ray directly on said screen in natural colors.

2. In a receiver for television or the like, a

cathode ray oscillograph tube having a luminous picture-reproducing screen, and means for varying the ray intensities in accordance with the intensities of the transmitted picture points, and means for causing the ray to scan over said screen in a given direction, said screen having a parallel ruling of recurrent, similar groups of at least three lines each, each line of a group having throughout its entire length a color different from the colors of the other lines of its group, said differently colored lines being formed by coatings of different salts, diflferently luminous under the influence of a cathode ray, whereby the transmitted picture is reproduced by the cathode ray directly on said screen in natural colors.

3. In a receiver for television or the like, a cathode ray oscillograph tube having a luminous picture-reproducing screen, and means for varying the ray intensities in accordance with the intensities of the transmitted picture points, and means for causing the ray to scan over said screen in a given direction, said screen having a parallel ruling of recurrent, similar groups of at least three lines each, each line of a group having throughout its entire length a color different from the colors of the other lines of its group, said ruling running in the scanning direction of the ray, said differently colored lines being formed by coatings of different salts, differently luminous under the influence of a cathode ray, whereby the transmitted picture is reproduced by the cathode ray directly on said screen in natural colors.

4. In a receiver for television or the like, a cathode ray oscillograph tube having a luminous picture-reproducing screen, and means for varying the ray intensities in accordance with the intensities oi the transmitted picture points, and means for causing the my to scan over said screen in a given direction, said screen having a parallel ruling of recurrent, similar groups of at least three lines each, each line of a group having throughout its entire length a color different from the colors of the other lines of its group, said. ruling running at right angles to the scanning direction of the ray, said differently colored lines being formed by coatings of difierent salts, differently luminous under the influence of a cathode ray, whereby the transmitted picture is reproduced by the cathode ray directly on said screen in natural colors.

REINHOLD RI jDENBERC-r. 

